Objective:
The overall objectives of this cooperative research project are 1) to scale-up, produce, and incorporate Lactobacillus reuteri into channel catfish feed, 2) to determine the efficacy of incorporation and viability of Lactobacillus reuteri and enzymatic activities in catfish feed, and 3) to determine catfish growth performance and feed utilization and efficiency following the diets containing fibrolytic enzymes expressed Lactobacillus reuteri.

Approach:
Fish diets contain high dietary fibers, in which most are not digested by catfish enzymes. These non-nutritive, indigestible fibers not only affect catfish digestion and absorption, but also may pollute the pond water environment. The hypothesis of this project is that the inclusion of fibrolytic enzymes expressed by Lactobacillus reuteri in catfish feed will improve cellulose digestion, increase body weight gain and enhance innate immunity of catfish. Beta-Glucanase and xylanase genes inserted in probiotic microorganism, which was developed by a scientist of National Taiwan University, will be incorporated into catfish basal diets that will be formulated to contain all nutrients to meet or exceed the requirements according to the National Research Council. After incorporation, the viability of the microorganism and enzymatic activities will be determined according to the established protocol. Catfish fingerlings in randomly assigned aquaria (three tanks per groups and three replicates per experiment) will be fed the experimental diets twice daily to apparent satiation for 10–12 weeks. Feed consumption will be determined by the weight of feed bottles after the last feeding each day and will be recorded. Fish will be counted and weighed in groups at two-week interval. At the end of six and 12 weeks, fish will be euthanized for sampling. Blood samples will be collected for hematological analysis (such as total Red Blood Count (RBC), White Blood count (WBC) counts and hematocrit). Serum lysozyme and myeloperoxidase activities, nitric oxide, complement activity will also be determined. Intestinal content will be collected for microfloral analysis by 16S ribosomal Ribonucleotic Acid (rRNA). Data will be analyzed by appropriate statistical methods.